What are tides? What causes the tides here on Earth?

Tides are the rise and fall of sea levels. The cause of tides on Earth is the combined effects of gravitational forces that are being exerted by the moon and the sun, and the earth's rotation

High tides and low tides are caused by the Moon. The Moon's gravitational pull generates something called the tidal force. The tidal force causes Earth and its water to bulge out on the side closest to the Moon and the side farthest from the Moon. These bulges of water are high tides.